Air compressor core

ABSTRACT

The present invention provides an air compressor core, comprising a drive assembly, a transmission assembly and a cylinder assembly, the drive assembly being arranged parallel to the cylinder assembly, the transmission assembly being arranged at a same end as the drive assembly and the cylinder assembly; and the drive assembly comprises a motor and the cylinder assembly comprises a cylinder, the motor being arranged parallel to the cylinder. With the air compressor core provided by the present invention, by the arrangement of the drive assembly parallel to the cylinder assembly and the arrangement of the transmission assembly at a same end as the drive assembly and the cylinder assembly, the utilization of the space structure of the entire core is optimized, without any waste of space. The overall size and volume of the air compressor may be effectively reduced.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of Chinese Patent Application No. 201510612997.0 filed on Sep. 24, 2015, the entire content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an air compressor core.

BACKGROUND OF THE PRESENT INVENTION

An air compressor core is to obtain high pressure gas, by driving a piston in a cylinder to move back and forth through a gearbox by a motor to compress gas in the cylinder. The compressed high pressure gas is output from the cylinder through an exhaust valve.

Due to the development of the technology and the requirements for portable applications, the volume of the air compressors is required to be minimized to meet various requirements like portable applications. A motor shaft in an existing air compressor core structure is perpendicular to a connecting rod of the piston or an axis of the cylinder. In such a structure, it is inconvenient to use a space of an inclined angle of the motor and the cylinder assembly, which is likely to result in waste of space. As a result, it is difficult to realize the miniaturization of the air compressors. Additionally, a drive wheel for the connecting rod is perpendicular to a plane constituted of the motor and the cylinder, the radius of the drive wheel directly influences the strokes of both the connecting rod and the piston. As a result, it is difficult to realize ultra-thin air compressors.

SUMMARY OF THE PRESENT INVENTION

The present invention is intended to provide an air compressor core which may effectively improve the utilization of the space of the core, and effectively reduce the thickness of the air compressor.

The present invention provides an air compressor core, including a drive assembly, a transmission assembly and a cylinder assembly, the drive assembly being arranged parallel to the cylinder assembly, the transmission assembly being arranged at a same end as the drive assembly and the cylinder assembly; and the drive assembly includes a motor and the cylinder assembly includes a cylinder, the motor being arranged parallel to the cylinder.

Further, the transmission assembly includes a driving gear, a transmission gear, a transition gear and a crank gear, a rotating shaft of the driving gear being perpendicular to a rotating shaft of the transmission gear; the transmission gear has coaxial spur teeth thereon, the driving gear is engaged with the transmission gear, the spur teeth on the transmission gear are engaged with the transition gear, and the transition gear is engaged with the crank gear; the motor drives the driving gear to rotate, the driving gear drives the transmission gear, the spur teeth of the transmission gear drive the transition gear, the transition gear drives the crank gear; and the crank gear is connected to a piston through a connecting rod which drives the piston to move within the cylinder.

Further, a cylinder head is provided at an end, far away from the crank gear, of the cylinder, and a pressure sensor is assembled on the cylinder head.

Further, an exhaust valve is provided between an air outlet and the cylinder head of the cylinder, and an exhaust valve spring is provided on the exhaust valve at an end of the cylinder head.

Further, a wearing ring is assembled at an internal end of the piston, and the position of the wearing ring relative to the piston is fixed; an annular groove is provided at an outer end of the piston, and a plurality of intake grooves uniformly distributed is provided in the periphery of an end surface of the outer end of the piston, with the intake groove and the annular groove being arranged alternately; and a piston seal ring is assembled on the annular groove.

Further, a nozzle seal ring is sleeved on a nozzle of the cylinder head; a threaded female nozzle is assembled to the nozzle seal ring, the threaded female nozzle being a round pipe having threads therein, the inner diameter of the threaded female nozzle being larger than the outer diameter of the nozzle seal ring; and a threaded female nozzle cover is mounted on the cylinder head, the opening diameter of the threaded female nozzle cover being smaller than the outer diameter of the threaded female nozzle.

Further, a piston seal ring and a wearing ring are sleeved on the piston, and the positions of the piston seal ring and the wearing ring relative to the piston are fixed; one end of the piston is connected to the connecting rod through a piston shaft, and a stepped hole is formed on the other end of the piston, with an intake valve, an intake valve spring and an intake valve cover being provided within the stepped hole from inside to outside, successively, the intake valve being a step structure; and the intake valve spring is sleeved on a narrow end of the intake valve, and the intake valve spring is resisted against the intake valve cover.

Further, the driving gear, the transmission gear, the transition gear and the crank gear are all arranged in a gearbox which mainly consists of a upper gearbox and a lower gearbox; and a first ball bearing is provided on each of a upper segment and a lower segment of a transmission gear shaft of the transmission gear, and a second ball bearing is provided on each of a upper segment and a lower segment of a transition gear shaft of the transition gear.

Further, the thickness of a PCB of the pressure sensor ranges from 0.6 mm to 2 mm; a piece of metal support is added outside the PCB, the metal support being secured onto the cylinder head through screws; and there is a pad on the PCB.

Further, the cylinder assembly includes a double-valve cylinder; a double-valve cylinder head is provided at one end, far away from the transmission assembly, of the double-valve cylinder, with an air inlet opening and an air outlet opening both provided on the double-valve cylinder head; both an air inlet and an air outlet of the double-valve cylinder are provided at one end, far away from the transmission assembly, of the double-valve cylinder; and an intake valve for the double-valve cylinder and an intake valve spring for the double-valve cylinder are successively arranged between the air inlet opening and the air outlet, and an exhaust valve spring for the double-valve cylinder and an exhaust valve for the double-valve cylinder are successively arranged between the air outlet opening and the air outlet.

With the air compressor core provided by the present invention, by the arrangement of the drive assembly parallel to the cylinder assembly and the arrangement of the transmission assembly at a same end as the drive assembly and the cylinder assembly, the utilization of the space structure of the entire core is optimized, without any waste of space, the overall size and volume of the air compressor may be effectively reduced; by the arrangement of a plane of the crank gear parallel to the plane constituted of the motor and the cylinder and the arrangement of gear surfaces of the transmission gear and the transition gear also parallel to the plane constituted of the motor and the cylinder, an implementation way for an efficient structure of an ultra-thin core is obtained, and the diameter of the crank gear and the stroke of the piston are not correlated with the thickness of the core; by the directly assembly of the pressure sensor on a cylinder head, an additional air pipe and a shell of the sensor required for traditional pressure measurement are omitted. Furthermore, the reliability of the pressure measurement is improved, and the design space of the air compressor is saved.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings described herein are provided for further understanding the present invention, and constitute a part of the application. Exemplary embodiments of the present invention and description of the exemplary embodiments are used for explaining the present invention, and not for inappropriately limiting the present invention. In the drawings:

FIG. 1 is a structural diagram schematically showing schematically showing, from one direction, an air compressor core according to embodiments of the present invention;

FIG. 2 is a structural diagram schematically showing, from another direction, the air compressor core according to the embodiments of the present invention;

FIG. 3 is a sectional view schematically showing a transmission assembly according to the embodiments of the present invention;

FIG. 4 is an exploded view schematically showing the air compressor core according to the embodiments of the present invention;

FIG. 5 is an overall structural diagram schematically showing a cylinder assembly according to the embodiments of the present invention;

FIG. 6 is an exploded view schematically showing the cylinder assembly according to the embodiments of the present invention;

FIG. 7 is a structural diagram schematically showing one state of a piston according to the embodiments of the present invention;

FIG. 8 is a structural diagram schematically showing another state of the piston according to the embodiments of the present invention;

FIG. 9 is a schematic diagram schematically showing a compression stroke direction of the piston according to the embodiments of the present invention;

FIG. 10 is a schematic diagram schematically showing an intake stroke direction of the piston according to the embodiments of the present invention;

FIG. 11 is a structural diagram schematically showing another piston according to the embodiments of the present invention;

FIG. 12 is an exploded view schematically showing another piston according to the embodiments of the present invention;

FIG. 13 is a schematic diagram schematically showing a compression stroke direction of the another piston according to the embodiments of the present invention;

FIG. 14 is a schematic diagram schematically showing an intake stroke direction of the another piston according to the embodiments of the present invention;

FIG. 15 is an overall structural diagram schematically showing a double-valve cylinder according to the embodiments of the preset invention;

FIG. 16 is an exploded view schematically showing the double-valve cylinder according to the embodiments of the present invention;

FIG. 17 is an overall structural diagram schematically showing a pump head assembly according to the embodiments of the present invention;

FIG. 18 is an exploded view schematically showing the pump head assembly according to the embodiments of the present invention; and

FIG. 19 is a sectional view schematically showing the pump head assembly according to the embodiments of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention will be described below in detail with reference to the accompanying drawings by embodiments.

Embodiment 1

Referring to FIG. 1 and FIG. 2, in this embodiment, an air compressor core is provided, including a drive assembly 46, a transmission assembly 47, a cylinder assembly 48 and a pump head assembly 49.

The drive assembly 46 is arranged parallel to the cylinder assembly 48, the transmission assembly 47 is arranged at a same end as the drive assembly 46 and the cylinder assembly 48, and the pump head assembly 49 is positioned at one end, far away from the transmission assembly 47, of the drive assembly 46. In this way, the utilization of the space structure of the entire core is optimized, without any waste of space. The overall size and volume of the air compressor may be effectively reduced.

In order to obtain an ultra-thin core, the thickness is controlled to be 20 mm; and the drive assembly 46 includes a motor 17 which is a 280 motor or 290 motor, both the upper surface and the lower surface of the motor 17 are flat surfaces parallel to each other and the distance between the two flat surfaces is smaller than or equal to 20 mm. The cylinder assembly 48 includes a cylinder 15, the outer diameter of which is controlled to be within 20 mm, and the motor 17 is arranged parallel to the cylinder 15; and the height of an upper surface and a lower surface of the pump head assembly 49 is also controlled to be within 20 mm. In this way, it is possible to control the thickness of the entire core to be within 20 mm.

In this embodiment, the transmission assembly 47 is also a critical design. As shown in FIG. 3 and FIG. 4, the transmission assembly 47 includes a driving gear 19, a transmission gear 34, a transition gear 30 and a crank gear 29, a rotating shaft of the driving gear 19 being perpendicular to a rotating shaft of the transmission gear 34; when the driving gear 19 is a spur gear, the transmission gear 34 is a crown gear; when the driving gear 19 is a conical gear, the transmission gear 34 is a bevel gear; the transmission gear 34 has coaxial spur teeth thereon, the driving gear 19 is engaged with the transmission gear 34, the spur teeth on the transmission gear 34 are engaged with the transition gear 30, and the transition gear 30 is engaged with the crank gear 29. The motor 17 drives the driving gear 19 to rotate, the driving gear 19 drives the transmission gear 34, the spur teeth of the transmission gear 34 drive the transition gear 30, and the transition gear 30 drives the crank gear 29; and the crank gear 29 is connected to a piston 21 through a connecting rod 24. A motor blade 16 is provided at one end, far away from the driving gear 19, of the motor 17.

The stroke of the piston 21 depends upon the diameter of the crank gear 29. In order to obtain an appropriate stroke of the piston, the diameter of the crank gear 29 cannot be too small. If the diameter of the crank gear 29 is 23.5 mm, according to a conventional design approach, the rotating shaft of the crank gear 29 is arranged parallel to a plane constituted of the motor 17 and the cylinder 15, that is, the plane of the crank gear 29 is perpendicular to the plane constituted of the motor 17 and the cylinder 15. In this case, the thickness of the core is at least required to be greater than the diameter of the crank gear 29. In the technical solution of this embodiment, the rotating shaft of the crank gear 29 is perpendicular to the plane constituted of the motor 17 and the cylinder 15. That is, the plane of the crank gear 29 is parallel to the plane constituted of the motor 17 and the cylinder 15. The gear planes of the transmission gear 34 and the transition gear 34 are also parallel to the plane constituted of the motor 17 and the cylinder 15. This is an implementation way to obtain an effective structure of an ultra-thin core. In such an implementation way, the diameter of the crank gear 29 and the stroke of the piston 21 are not correlated with the thickness of the core.

The driving gear 19, transmission gear 34, the transition gear 30 and the crank gear 29 are all arranged in a gearbox which mainly consists of a upper gearbox 37 and a lower gearbox 36; and a first ball bearing 33 is provided on each of a upper segment and a lower segment of a transmission gear shaft 35 of the transmission gear 34, a second ball bearing 27 is provided on each of a upper segment and a lower segment of a transition gear shaft 31 of the transition gear 30, and corresponding bearing seats are provided in the upper gearbox 37 and the lower gearbox 36. In this way, it is ensured that the transmission gear 34 is parallel to the transition gear 30, the transmission resistance between the gears is effectively reduced, and consequently, the transmission efficiency of the system is improved.

A foolproof positioning column, i.e. a stud, is provided on the lower gearbox 36. The screw 38 is locked, just after fastening covers of the upper gearbox 37 and the lower gearbox 36 through the foolproof stud. The motor 17 is secured on one side of the cylinder 15 through a motor securing screw 20 and a motor gasket 18, and the motor gasket 18 may effectively reduce the clearance and mechanical vibration between the motor 17 and the cylinder 15.

In order to prevent the transition gear 30 from moving due to the operation of the gearbox, a positioning sleeve 32 is provided on the transition gear 30 for the purpose of limitation. The transition gear 30 drives the crank gear 29, and the crank gear 29 drives the connecting rod 24 to move back and forth. The crank gear 29 is secured on the lower gearbox 36 through a hobnail 28, the diameter of the head of which is greater than the diameter of the rotating shaft of the crank gear 29, and this may prevent the crank fear 29 from falling off when running at a high speed. The crank gear 29 is connected to the connecting rod 24 through a crank 26 which is connected to the connecting rod 24 through the second ball bearing 27. As a result, the resistance for the crank 26 to drive the connecting rod 24 is reduced.

A cylinder head 7 is provided at an end, far away from the crank gear 29, of the cylinder 15. The cylinder head 7 is secured on the cylinder 15 through a screw for securing the cylinder head 6, and a pressure sensor 9 is directly assembled on the cylinder head 7. In this way, an additional air pipe and a shell of the sensor required for a traditional pressure measurement are omitted. Hence, the reliability of the pressure measuring is improved, and the design space of the air compressor is saved. The pressure sensor 9 seals the pressure sensor 9 and the cylinder head 7 through a pressure sensor seal ring 8. The thickness of a PCB of the pressure sensor 9 ranges from 0.6 mm to 2 mm. In order to bear impact of high pressure without any deformation of the PCB which influences the tightness, a piece of metal support 10 is added outside the PCB of the sensor. The metal support 10 is secured onto the cylinder head 7 through screws 11, in order to provide strong support to the pressure sensor 9. There is a pad on the PCB of the sensor, and the pad is provided to weld the PCB of the sensor and to control wires of the PCB for powering and data communication.

Referring to FIG. 5 and FIG. 6, the cylinder 15 is a single-valve cylinder. An exhaust valve 14 is provided between an air outlet and the cylinder head 7 of the cylinder 15, and an exhaust valve spring 13 is mounted on the exhaust valve 14 at an end of the cylinder head 7, and an air outlet seal ring 12 is further provided between the cylinder 15 and the cylinder head 7. When the connecting rod 24 drives the piston 21 to move within the cylinder 15 in order to compress the air, as the pressure in the cylinder 15 is larger than the pressure in the cylinder head 7, the air pushes against the exhaust valve 14 so that the high pressure gas comes into the cylinder head 7. When there is a balance between the pressure in the cylinder 15 and the pressure in the cylinder head 7, the exhaust valve spring 13 pushes the exhaust valve 14 to block the air outlet of the cylinder 15. When the connecting rod 24 pulls the piston 21 back, as the pressure in the cylinder 15 is lower than the pressure in the cylinder head 7, the exhaust valve spring 13 pushes the exhaust valve 14 to seal the air outlet of the cylinder 15, and this may prevent the high pressure gas from flowing back to the cylinder 15. The connecting rod 24 is connected to the piston 21 through the piston shaft 25, and this may effectively ensure the linearity of the stroke of the piston so that the stroke of the piston will not swing up and down with the connecting rod 24.

Referring to FIG. 7, FIG. 8, FIG. 9 and FIG. 10, the design and working principle of a single-valve cylinder piston will be described below in detail. A wearing ring 23 is assembled at an internal end of the piston 21 (i.e. one end far away from the air outlet of the cylinder 15); an annular groove 51 is provided at an outer end of the piston 21 (i.e. one end close to the air outlet of the cylinder 15); a plurality of intake grooves 50 uniformly distributed is provided in the periphery of an end surface of the outer end of the piston 21 (in this embodiment, there are four intake grooves 50 uniformly distributed in the periphery of a front end of the piston 21), the section of the intake groove 50 may be “U”-shaped, “V”-shaped or of other shapes; the intake groove 50 and the annular groove 51 are arranged alternately; and a piston seal ring 22 is assembled on the annular groove 51.

The position of the wearing ring 23 relative to the piston 21 is fixed, and the wearing ring 23 is mainly used for balancing the piston 21. When the piston 21 moves back and forth at a high speed within the cylinder 15 with the connecting rod 24, the wearing ring 23 may ensure that an axis of the piston 21 is parallel to and overlaps an axis of the cylinder 24 as far as possible, thus to reduce the friction loss of the piston seal ring 22.

When the piston 21 moves toward the air outlet of the cylinder 15, the cylinder 15 rubs the piston seal ring 22, so that the piston seal ring 22 moves to the innermost end of the stroke of the piston seal ring 22 (i.e. the innermost end of the annular groove 51), automatically, as shown in FIG. 9. In this way, the piston seal ring 22 may seal the intake groove 50 on the piston 21 to prevent the compressed gas from escaping from this end. The piston 21 continues to operate, and the air within the cylinder 15 is continually compressed until the piston 21 finishes the whole compression stroke.

After finishing the whole compression stroke, the piston 21 comes back to an intake stroke. When the intake stroke starts, the piston seal ring 22 is pulled to the outermost end of the stroke of the piston seal ring 22 (i.e. the outermost end of the annular groove 51) by the friction of a wall of the cylinder 15, as shown in FIG. 10. At this moment, the inlet groove 50 on the piston 21 is opened, and the outside air enters the cylinder 15 through the intake groove 50. This is repeated to introduce air into the cylinder and then compress the air.

Referring to FIG. 11, FIG. 12, FIG. 13 and FIG. 14, the design and working principle of another single-valve cylinder piston will be described below in detail. In this implementation way, a piston seal ring 22 and a wearing ring 23 are sleeved on the piston 21, and the positions of the piston seal ring 22 and the wearing ring 23 relative to the piston 21 are fixed, that is, there is no stroke of the piston seal ring 22. One end of the piston 21 is connected to the connecting rod 24 through a piston shaft 25, and a stepped hole 61 is formed on the other end of the piston 21, with an intake valve 66, an intake valve spring 65 and an intake valve cover 64 being provided within the stepped hole from inside to outside, successively. The intake valve 66 is a step structure; and the intake valve spring 65 is sleeved on a narrow end of the intake valve 66, and the intake valve spring 65 is resisted against the intake valve cover 64.

When the piston 21 performs a compression stroke, a wide end of the intake valve 66 seals the air inlet due to the intake valve spring 65 and the pressure in the cylinder 21, as shown in FIG. 13, so that the piston finishes compressing the air. When the piston 21 performs an intake stroke, when the pressure in the cylinder 15 is lower than the pressure outside the cylinder 15, the intake valve 66 will be opened by the air outside the cylinder 15 and the air enters the cylinder 15, as shown in FIG. 14, so that the intake process is finished. The intake valve spring 65 between the intake valve 66 and the intake valve head 64 may ensure that the intake valve 66 will not contact the intake valve cover 64, thus to unblock the air inlet channel.

The air outlet opening of the cylinder head 7 is directly connected to an air delivery pipe. In order to make the length of the air compressor core as short as possible, an implementation of separating the air pipe from the core is employed, where the air pipe is connected to the cylinder head 7 through the pump assembly 49. As shown in FIG. 17, FIG. 18 and FIG. 19, the pump assembly 49 includes a nozzle seal ring 5 which is sleeved on the nozzle of the cylinder head 7. The inner diameter of the nozzle seal ring 5 is slightly smaller than the outer diameter of the nozzle of the cylinder head 7, and the nozzle seal ring 5 is assembled on the nozzle in aid of the tension of the seal ring 5. A threaded female nozzle 4 is assembled on the nozzle seal ring 5, the threaded female nozzle 4 being a round pipe having threads therein, the inner diameter of the threaded female nozzle 4 being larger than the outer diameter of the nozzle seal ring 5, which is convenient for assembly; and meanwhile, there may be a relative distance between the threaded female nozzle 4 and the nozzle seal ring 5. A threaded female nozzle cover 2 is mounted on the cylinder head 7, and the threaded female nozzle cover 2 is tightly secured onto the cylinder head 39 through a set screw 3. The opening diameter of the threaded female nozzle cover 2 is smaller than the outer diameter of the threaded female nozzle 4, and in this way, the threaded female nozzle 4 may be defined between the threaded female nozzle cover 2 and the nozzle of the cylinder head 7. A vibration absorber 1 is further sleeved on the threaded female nozzle cover 2.

When an external air pipe is inserted by threads into the threaded female nozzle 4, the threaded female nozzle 4 will be against an inner wall of the threaded female nozzle cover 2, so that the threads of the external air pipe closely contact the nozzle seal ring 5 when rotating to the bottom so as to finish sealing the clearance between the threads of the external air pipe and the nozzle of the cylinder head 7. In this way, the compressed air in the cylinder head 7 may be output along the inserted air pipe.

Embodiment 2

This embodiment provides an air compressor core which has the following differences compared to Embodiment 1: instead of the single-valve cylinder, a double-valve cylinder 45 is employed; and instead of the cylinder head 7, a double-cylinder head 39 is employed. An air outlet and an air inlet of the single-valve cylinder are at both ends of the cylinder 15, respectively, and an air outlet and an air inlet of the double-valve cylinder 45 are at a same end of the double-valve cylinder 45 in order to meet specific application requirements.

As shown in FIG. 15 and FIG. 16, an air inlet opening and an air outlet opening are both arranged on the double-valve cylinder head 39, and the air inlet and the air outlet of the double-valve cylinder 45 are both arranged on one end, far away from the transmission assembly 47, of the body of the double-valve cylinder 45. The air inlet opening and the air inlet are arranged opposite to each other, and the air outlet opening and the air outlet are arranged opposite to each other. A “8”-shaped seal ring 40 is provided between the double-valve cylinder head 39 and the double-valve cylinder 45. A double-valve cylinder intake valve 41 and a double-valve cylinder intake valve spring 42 are successively arranged between the air inlet opening and the air outlet, and a double-valve cylinder exhaust valve 43 and a double-valve cylinder exhaust valve spring 44 are successively arranged between the air outlet opening and the air outlet.

A piston seal ring 22 and a wearing ring 23 are sleeved on the piston 21 in this embodiment, and the positions of the piston seal ring 22 and the wearing ring 23 relative to the piston 21 are fixed, that is, there is no stroke of the piston seal ring 22. Additionally, there is no intake valve provided on the piston 21.

When the piston 21 performs a compression stroke, the double-valve cylinder intake valve 41 blocks the air inlet opening of the double-valve cylinder head 39, and the double-valve cylinder exhaust valve 44 opens the air outlet of the double-valve cylinder 45; and when the piston 21 performs a return stroke, the double-valve cylinder exhaust valve 44 blocks the air outlet of the double-valve cylinder 45, and the double-valve cylinder intake valve 41 opens the air inlet opening of the double-valve cylinder head 39.

The assembly position of the pressure sensor 9 is connected to the air outlet opening of the double-valve cylinder head 39, and this ensures that what is collected by the pressure sensor 9 is a real-time pressure value of the output air. Such a design has an advantage that the air inlet and the air outlet are at a same end of the double-valve cylinder 45. Additionally, the air outlet may be used for inflating an object, and the air inlet may be used for pumping out an object.

It may be seem from the above description, with the air compressor core provided by the embodiments of the present invention, the following technical effects will be achieved:

1. By the arrangement of the drive assembly 46 parallel to the cylinder assembly 48, and by the arrangement of the transmission assembly 47 at a same end as the drive assembly 46 and the cylinder assembly 47, the utilization of the space structure of the entire core is optimized, without any waste of space, and the overall size and volume of the air compressor may be effectively reduced.

2. The plane of the crank gear 29 is parallel to the plane constituted of the motor 17 and the cylinder 15, and the gear planes of the transmission gear 34 and the transition gear 34 are also parallel to the plane constituted of the motor 17 and the cylinder 15. This is an implementation way to obtain an effective structure of an ultra-thin core. In such an implementation way, the diameter of the crank gear 29 and the stroke of the piston 21 are not correlated with the thickness of the core.

3. A pressure sensor 9 is directly assembled on the cylinder head 7. In this way, an additional air tube and a shell of the sensor required for a traditional pressure measurement are omitted. Hence, the reliability of the pressure measuring is improved, and the design space of the air compressor is saved.

The foregoing descriptions are merely the preferred embodiments of the present invention, and the present invention is not limited thereto. Various alternations and variations may be made by a person of ordinary skill in the art. Any modification, equivalent replacement and improvement should be regarded as falling into the protection scope of the present invention without departing from the spirit and principle of the present invention. 

What is claimed is:
 1. An air compressor core, comprising a drive assembly, a transmission assembly and a cylinder assembly, the drive assembly being arranged parallel to the cylinder assembly, the transmission assembly being arranged at a same end as the drive assembly and the cylinder assembly; wherein the drive assembly comprises a motor and the cylinder assembly comprises a cylinder, the motor is arranged parallel to the cylinder.
 2. The air compressor core according to claim 1, wherein the transmission assembly comprises a driving gear, a transmission gear, a transition gear and a crank gear, a rotating shaft of the driving gear being perpendicular to a rotating shaft of the transmission gear; the transmission gear has coaxial spur teeth thereon, the driving gear is engaged with the transmission gear, the spur teeth on the transmission gear are engaged with the transition gear, and the transition gear is engaged with the crank gear; the motor drives the driving gear to rotate, the driving gear drives the transmission gear, the spur teeth of the transmission gear drive the transition gear, the transition gear drives the crank gear; and the crank gear is connected to a piston through a connecting rod which drives the piston to move within the cylinder.
 3. The air compressor core according to claim 2, wherein a cylinder head is provided at an end, far away from the crank gear, of the cylinder, and a pressure sensor is assembled on the cylinder head.
 4. The air compressor core according to claim 3, wherein an exhaust valve is provided between an air outlet and the cylinder head of the cylinder, and an exhaust valve spring is provided on the exhaust valve at an end of the cylinder head.
 5. The air compressor core according to claim 2, wherein a wearing ring is assembled at an internal end of the piston, and the position of the wearing ring relative to the piston is fixed; an annular groove is provided at an outer end of the piston, and a plurality of intake grooves uniformly distributed is provided in the periphery of an end surface of the outer end of the piston, with the intake groove and the annular groove being arranged alternately; and a piston seal ring is assembled on the annular groove.
 6. The air compressor core according to claim 3, wherein a nozzle seal ring is sleeved on a nozzle of the cylinder head; a threaded female nozzle is assembled to the nozzle seal ring, the threaded female nozzle being a round pipe having threads therein, the inner diameter of the threaded female nozzle being larger than the outer diameter of the nozzle seal ring; and a threaded female nozzle cover is mounted on the cylinder head, the opening diameter of the threaded female nozzle cover being smaller than the outer diameter of the threaded female nozzle.
 7. The air compressor core according to claim 2, wherein a piston seal ring and a wearing ring are sleeved on the piston, and the positions of the piston seal ring and the wearing ring relative to the piston are fixed; one end of the piston is connected to the connecting rod through a piston shaft, and a stepped hole is formed on the other end of the piston, with an intake valve, an intake valve spring and an intake valve cover being provided within the stepped hole from inside to outside, successively, the intake valve being a step structure; and the intake valve spring is sleeved on a narrow end of the intake valve, and the intake valve spring is resisted against the intake valve cover.
 8. The air compressor core according to claim 2, wherein the driving gear, the transmission gear, the transition gear and the crank gear are all arranged in a gearbox which mainly consists of a upper gearbox and a lower gearbox; and a first ball bearing is provided on each of a upper segment and a lower segment of a transmission gear shaft of the transmission gear, and a second ball bearing is provided on each of a upper segment and a lower segment of a transition gear shaft of the transition gear.
 9. The air compressor core according to claim 3, wherein the thickness of a PCB of the pressure sensor ranges from 0.6 mm to 2 mm; a piece of metal support is added outside the PCB, the metal support being secured onto the cylinder head through screws; and there is a pad on the PCB.
 10. The air compressor core according to claim 1, wherein the cylinder assembly comprises a double-valve cylinder; a double-valve cylinder head is provided at one end, far away from the transmission assembly, of the double-valve cylinder, with an air inlet opening and an air outlet opening both provided on the double-valve cylinder head; both an air inlet and an air outlet of the double-valve cylinder are provided at one end, far away from the transmission assembly, of the double-valve cylinder; and an intake valve for the double-valve cylinder and an intake valve spring for the double-valve cylinder are successively arranged between the air inlet opening and the air outlet, and an exhaust valve spring for the double-valve cylinder and an exhaust valve for the double-valve cylinder are successively arranged between the air outlet opening and the air outlet. 